Fix implementation of the likely resolution of core issue 253 to support class based arrays.

[itessier]

Summary

D16552 implemented the likely resolution of core issue 253, but didn't include support for class based array fields. E.g.:

struct A {
}

struct B {

A a[2];

}

const B b; // Fails, but should pass.

[rsmith]

Committed as rL285430.

lib/AST/DeclCXX.cpp

if (T->isReferenceType()) {
 
       // C++0x [class]p7:
       //   A standard-layout class is a class that:
       //    -- has no non-static data members of type [...] reference,
       data().IsStandardLayout = false;
     }
 
     if (!Field->hasInClassInitializer() && !Field->isMutable()) {
-      if (CXXRecordDecl *FieldType = Field->getType()->getAsCXXRecordDecl()) {
+      if (CXXRecordDecl *FieldType = T->getAsCXXRecordDecl()) {
         if (FieldType->hasDefinition() && !FieldType->allowConstDefaultInit())
           data().HasUninitializedFields = true;
       } else {
         data().HasUninitializedFields = true;
       }
     }
 
     // Record if this field is the first non-literal or volatile field or base.

test/SemaCXX/constexpr-value-init.cpp

 static_assert(D().c == 0, "");
 static_assert(D().d == 0, "");
 
 struct V : virtual C {};
 template<typename T> struct Z : T {
   constexpr Z() : V() {}
 };
 constexpr int n = Z<V>().c; // expected-error {{constant expression}} expected-note {{virtual base class}}
+
+struct E {
+  A a[2];
+};
+constexpr E e; // ok
+static_assert(e.a[0].a == 1, "");
+static_assert(e.a[0].b == 2, "");
+static_assert(e.a[1].a == 1, "");
+static_assert(e.a[1].b == 2, "");